git-imap-send: Support SSL

Allow SSL to be used when a imaps:// URL is used for the host name.

Also, automatically use TLS when not using imaps:// by using the IMAP
STARTTLS command, if the server supports it.

Tested with Courier and Gimap IMAP servers.

Signed-off-by: Robert Shearman <robertshearman@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-compat-util.h

@@ -99,6 +99,11 @@
 #include <iconv.h>
 #endif
 
+#ifndef NO_OPENSSL
+#include <openssl/ssl.h>
+#include <openssl/err.h>
+#endif
+
 /* On most systems <limits.h> would have given us this, but
  * not on some systems (e.g. GNU/Hurd).
  */